1. Field of the Invention
The present invention relates to a tool exchanger for exchanging tools between a machine tool spindle and a tool magazine.
2. Description of the Prior Art
In a typical tool exchanger, as disclosed in U.S. Pat. No. 3,218,706 to Zankl et al., there is provided an exchange arm which is rotatable about and slidable along an axis for exchanging the tool between a machine tool spindle and a tool magazine. The exchange arm is formed with a pair of semi-circular openings at opposite ends thereof and slidably carries therein a pair of gripping plungers, which are spring-biased toward the opposite ends of the exchange arm for gripping tools held in the semi-circular openings. The gripping plungers are forced by the tools to be retracted inwardly of the exchange arm at the time when the exchange arm is pivoted in one direction around a tool grip position and when the exchange arm is pivoted in the other direction from a gripped position to a parked position.
The force that effects such inward retraction movements of the gripping plungers typically counteracts the tools. In the case where the tool magazine used with the tool exchanger is of a chain type wherein tools are customarily stored in tool sockets carried on a chain, such counteraction force causes the tool at a tool exchange station to be displaced therefrom due to the presence of looseness in the chain, thus obstructing smooth and exact tool gripping.